• Journal of the Semiconductor & Display Technology
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• v.6 no.3
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• pp.13-17
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• 2007

Effect of Co substitution on crystal structures of two nickel silicides, NiSi and $NiSi_2$, is investigated by using an ab initio calculation. Relaxed NiSi and $NiSi_2$ structures are calculated and the calculated lattice parameters are in good agreement with experimentally determined lattice parameters within about 2%. A Co atom substitutes a Ni and Si site, respectively, to evaluate the preferable site between them. Co prefers Ni site to Si site in both NiSi and $NiSi_2$. The calculated total energy also indicates that the Co substitution to Ni site stabilizes both the NiSi and $NiSi_2$ structures. Co also prefers Ni site in $NiSi_2$ to that in NiSi, indicating that $NiSi_2$ becomes more stable than NiSi with Co substitution. As Co addition to NiSi improves its thermal stability experimentally, this indicates that the energy barrier between the two phases is high enough to prevent the phase transformation from NiSi to $NiSi_2$ up to high temperature.

• Korean Journal of Materials Research
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• v.17 no.7
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• pp.358-360
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• 2007

Cobalt subtitution on NiSi is investigated by using an ab-initio calculation. Firstly, a relaxed NiSi structure is calculated and the calculated lattice parameters are compared with experimentally determined lattice parameters. The calculated values are smaller than the experimental values by about 2%. As the calculation is based on 0 K, and the experimental measurement is performed at room temperature, those values are in good agreement. Next, a Co atom substitutes a Ni and Si site, respectively, to evaluate the preferable site between them. Co prefers Ni site to Si site. The calculated total energy also indicates that the Co substitution to Ni site stabilizes the NiSi structure. Therefore, the thermal stability of NiSi with Co addition can be achieved by the structure stabilization of NiSi by Co substitution into Ni site of NiSi.

• Journal of Powder Materials
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• v.9 no.1
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• pp.19-24
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• 2002

This paper reports the results of an investigation into the effect of Cu additions upon the nano-crystallization behaviour of an Al-Y-Ni alloy. 1 at.% Cu was added to a base alloy of Al/sub 88/Y₄Ni/sub 8/ either by substitution for Al to form Al/sub 87/Y₄Ni/sub 8/Cu₁, or by substitution for Ni to form Al/sub 88/Y₄Ni/sub 7/Cu₁. Consistent with previous findings in the literature, the substitution of Cu for Al was found to increase the thermal stability of the amorphous phase whereas the substitution of Cu for Ni was found to decrease its thermal stability. Comparing the microstructures of these alloys after heat treatment to produce equivalent volume fractions of Al nanocrystals showed average grain sizes of 14 nm, 12 nm and 9 nm for the alloys Al/sub 88/Y₄Ni/sub 8/, Al/sub 87/Y₄Ni/sub 8/Cu₁respectively. The effect of Cu in refining the size of the nanocrystals was attributed to enhanced nucleation increasing the number density of the nanocrystals, rather than diffusion limited or interface limited growth.

• Journal of the Semiconductor & Display Technology
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• v.7 no.4
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• pp.41-44
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• 2008

NiSi is less stable than the previously-used $CoSi_2$ at high temperature. Some noble metals, such as Pd and Pt, have been added to NiSi to improve its thermal stability. We employed a first principles calculation to understand the Pd segregation at the interface. An orthorhombic structure of NiSi was used to construct an orthorhombic-NiSi/Si (010). Lattice parameters along a- and c-axes in orthorhombic-NiSi were matched with those of Si for epitaxy contact. The optimized $1\times4\times1$ orthorhombic-NiSi (010) and $1\times2\times1$ Si (010) superstructures were put together to construct the orthorhombic-NiSi/Si (010), and the superstructure was relieved in calculation to minimize its total free energy. The optimized interface thickness of the superstructure was $1.59\AA$. Pd atom was substituted in Ni and Si sites located near interface. Both Ni and Si sites located at the interface were favorable for Pd substitution.

• Journal of the Korean Ceramic Society
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• v.14 no.3
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• pp.187-192
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• 1977

For the purpose researching to the influence of tetrahedral and octahedral preference of cations of $Ni^{2+}$, $Ti^{4+}$ upon the formation and the color development of the $ZnO-SnO_2$ spinel containing $Ni^{2+}$ and $Ti^{4+}$ ions, the gradual substitution of $Ni^{2+}$ ions for $Zn^{2+}$ ions and of $Ti^{4+}$ ions for $Sn^{4+}$ ions of the spinel in NiO-ZnO-$SnO_2$-$TiO_2$ system was carried out. On samples prepared by calcining the oxide and basic cabonate mixtures at $1300^{\circ}C$ for 2 hours, the X-ray analysis, measurement of reflectance and the test of their stabilaity as a glaze pigment were also carried out. The results are summarized as follows 1) Single spinel was formed completely to x=1 in the $xNiO\cdot(2-x)ZnO\cdot{SnO}_2$system, and gave brilliant lightgreen hue. Moreover, $NiO\cdot{ZnO}\cdot{SnO}_2$ formed easily spinel than $NiO\cdot{MgO}\cdot{SnO}_2$ because Zn^{2+}$ ions had more strong tetrahedral preference than $Mg^{2+}$ ions. 2) As the gradual substitution of $Ti^{4+}$ ions for $Sn^{4+}$ ions in $NiO\cdot{MgO}\cdot{SnO}_2$ system, the spinels formed well and was nearly not changed in the hue. 3) The results of glaze test. (1) As the gradual substitution of $Ni^{2+}$ ions for $Zn^{2+}$ ions, the color changed from dull white to graish broun gradually in calcium-zinc glaze and calcium glaze, and from white to beige in tile glaze. (2) As the gradual substitution of $Ti^{4+}$ ions for $Sn^{4+}$ ions in $NiO-ZnO-SnO_2-TiO_2$ system, the color was become dull generally and was not change in tile glaze.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.434-437
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• 2001

In this study piezoelectric and dielectric properties of $Pb(Mn_{1/3}Nb_{2/3})O_{3}-Pb(Zr,Ti)O_{3}$ ceramics were investigated with $Pb(Ni_{1/3}Nb_{2/3})O_{3}$ substitution. As the $Pb(Ni_{1/3}Nb_{2/3})O_{3}$ substitution was increased, dielectric constant and electromechanical coupling factor (kp) were increased while mechanical quality factor decreased.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.434-437
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• 2001

In this study piezoelectric and dielectric properties of Pb(Mn$\sub$1/3/Nb$\sub$2/3/)O$_3$-Pb(Zr,Ti)O$_3$ ceramics were investigated with Pb(Ni$\sub$1/3/Nb$\sub$2/3/)O$_3$ substitution. As the Pb(Ni$\sub$1/3/Nb$\sub$2/3/)O$_3$) substitution was increased, dielectric constant and electromechanical coupling factor (kp) were increased while mechanical quality factor decreased.

• Journal of Electrochemical Science and Technology
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• v.15 no.1
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• pp.161-167
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• 2024

Despite the important role of manganese (Mn) in cobalt-free, Ni-rich cathode materials, existing reports on the effects of Mn as a substitute for cobalt are not consistent. In this work, we analyzed the performance of cathodes comprised of Li(Ni_1-xMn_x)O₂ (LNMO). Both beneficial and detrimental results occurred as a result of the Mn substitution. We found that a complex interplay of effects (Li/Ni mixing driven by magnetic frustration, grain growth suppression, and retarded lithium insertion/extraction kinetics) influenced the performance and was intimately related to calcination temperature. This indicates the importance of establishing an optimal reaction temperature for the development of high-performance LNMO.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.1
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• pp.160-168
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• 1998

In order to investigate the color variation and the solubility limit in wagnerites by metal ion substitution, wagnerite ($A_2XO_4Z$) was synthesized and then, substituted by coloring metal ions, especially $CO^{2+},Ni^{2+}$ and $Cu^{2+}$ ions. When calcium was replaced with Mg, Co, Ni and Cu divalent ions, solid solutions were formed with a limited solubility. Single phase wagnerites were synthesized by the substitution of Ca with Mg and Co, and their colors were white and purple, respectively. Substitutions with $Li^+$ were succeeded in the specific composition and the substitution of vanadium for $X^{5+}$ were attempted, resulting in the wagnerites of dark purple, dark gold and light yellow colors. The substitution of chlorine was, also, attmepted for the fluorine site.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.1
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• pp.35-39
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• 2006

In this study, in order to develop the multilayer piezoelectric actuator and ultrasonic resonator, PMN-PNN-PZT ceramics were fabricated by sintering with $Li_2CO_3-Na_2CO_3$ as sintering aids at $950^{\circ}C$ and their piezoelectric and dielectric characteristics were investigated as a function of PNN substitution. With increasing PNN substitution, dielectric constant(${\epsilon}_r$), electromechanical coupling factor(kp), and piezoelectric d constant($d_{33}$) were increased to $12 mol\%$ PNN substitution and then showed a tendency to decrease rapidly With increasing PNN substitution, crystal structure changed from tetragonal to rhombohedral at $12 mol\%$ PNN substitution and then secondary phase was appeared and its intensity was increased. At the $12 mol\%$ PNN substituted PMN-PZT composition ceramic sintered at $950^{\circ}C$, density, kp, $d_{33}$ and Qm showed the optimum value of $7.79 g/cm^3$, 0.599, 419 pC/N, and 894, respectively for multilayer piezoelectric actuator application.